The angular range of effective pinning by one-dimensional artificial pinning centers in BaZrO3/YBa2Cu3O7-x nanocomposite films

• Main Authors: Victor Ogunjimi, Bibek Gautam, Mary Ann Sebastian, Timothy Haugan, Judy Wu
• Format: Article
• Language: English
• Published: AIP Publishing LLC 2019-08-01
• Series: AIP Advances
• Online Access: http://dx.doi.org/10.1063/1.5097703

Nanoscale c-axis-aligned one dimensional artificial pinning centers (1D-APC) in superconducting YBa2Cu3O7-x (YBCO) films have been shown to provide strong correlated pining to magnetic vortices at magnetic field H//c-axis. A question arises on how the pinning effectiveness is sustained as the H-orientation (θ) deviates from the c-axis and how such an angular range is correlated to the pinning efficiency of an individual 1D-APC. To shed lights on this question, this work investigates the angular range of pinning effectiveness of the BaZrO3 (BZO) 1D-APCs in BZO/YBa2Cu3O7-x nanocomposites as the strain field overlap is systematically varied by increasing the BZO doping level in the range of 2-6 vol.% and by the introduction of the secondary Y2O3 nanoparticles (3D APCs). By evaluating the maximum pinning force density (Fp, max), its location Hmax, and the α values of the nanocomposites normalized to that of the reference YBa2Cu3O7-x film as functions of θ at temperatures of 65–77 K, a quantitative correlation between the pinning efficiency of the BZO 1D-APCs and their effective angular range was obtained. In most samples, the 1D-APCs can provide enhanced Hmax in the range of θ ∼0°-60°. However, the Fp, max values only in nanocomposites with high pinning efficiency 1D-APCs exceed that of the YBa2Cu3O7-x over a smaller range up to θ ∼ 37°. Finally, the introduction of 3D APCs results in reduction of the α values over nearly the entire angular range. This study reveals the importance in improving individual 1D-APC’s pinning efficiency and hence extending its angular range of effective pinning.